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Thread: barrle Nut loctite

  1. #11
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    Quote Originally Posted by bananaman View Post
    I thought the grease was to prevent corrosion/welding between dissimilar metals (steel barrel and aluminum lower). Anybody have an authoritative answer?
    Thread galling is about the same as welding or seizing. The moly prevents this so that the parts maybe disassembled without destroying them.

    .
    Last edited by AMMOTECH; 08-06-11 at 21:54.
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  2. #12
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    The specified moly grease does several things. It allows the two or three "pre torques" to seat the threads without galling and seizing. Second, it acts as a seal to keep contaminents out of the threads so the barrel nut can be removed in the future without stripping the aluminum threads. Third, it prevents galvanic corrosion that would act to seize the threads.

    While copper or silver based antiseize compounds will work to prevent initial seizing they may not work over the long haul to protect the threads.

    The barrel nut torque values were determined using a specified lubricant. These values are not necessarily correct for other types of thread lubricants.

  3. #13
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    Quote Originally Posted by Heavy Metal View Post
    In fact, it needs moly-disulfide grease to prevent thread galling.
    I thought the grease was to prevent corrosion/welding between dissimilar metals (steel barrel and aluminum lower). Anybody have an authoritative answer?
    Last edited by bananaman; 08-06-11 at 22:36.
    "The human race divides politically into those who want people to be controlled and those who have no such desire." - Robert A. Heinlein

  4. #14
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    Thanks for the apparently time-traveling responses that actually appear to precede my first post (weird).

    Now that the no loctite answer is unanimous, a related question:

    What is the deal with 2 or 3 "pre torques" for the barrel nut? I've read others recommend it too but just never heard of it being done on any other machines (aircraft, auto engines, etc). I'm not a mechanic by trade or training, just an interested amateur wanting to build the best rifle I can.
    Last edited by bananaman; 08-06-11 at 22:48.
    "The human race divides politically into those who want people to be controlled and those who have no such desire." - Robert A. Heinlein

  5. #15
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    Quote Originally Posted by DBR View Post
    The specified moly grease does several things. It allows the two or three "pre torques" to seat the threads without galling and seizing. Second, it acts as a seal to keep contaminents out of the threads so the barrel nut can be removed in the future without stripping the aluminum threads. Third, it prevents galvanic corrosion that would act to seize the threads.

    While copper or silver based antiseize compounds will work to prevent initial seizing they may not work over the long haul to protect the threads.

    The barrel nut torque values were determined using a specified lubricant. These values are not necessarily correct for other types of thread lubricants.
    This^.

    Bananaman-The corrosion of dissimilar metals is the galling others have mentioned mentioned above...
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  6. #16
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    I haven't seen it in other trades either. I thought it counter-intuitive as I have stripped many aluminum threads by repeated torquing. The goal is to align the holes/notches in the barrel nut for the gas tube while staying within 30-80 ft-lbs. Depending on how far the next notch is, you may approach the upper end of the limit. As I understand it, the 2-3 torque method helps you precisely get to the next notch while slowly working the threads without stripping them.

    Quote Originally Posted by bananaman View Post
    What is the deal with 2 or 3 "pre torques" for the barrel nut? I've read others recommend it too but just never heard of it being done on any other machines (aircraft, auto engines, etc). I'm not a mechanic by trade or training, just an interested amateur wanting to build the best rifle I can.
    Galvanic corrosion is a chemical damage and occurs between dissimilar metals because of their differences in electronegativity. It is usually only a major concern when the mating parts are in contact with an ionic solution (salt water)

    http://www.engineersedge.com/galvanic_capatability.htm

    Galling is a physical damage and is the bitch of aluminum. Its caused by two materials sliding against each other.

    http://en.wikipedia.org/wiki/Galling

    Quote Originally Posted by *Paladin* View Post
    The corrosion of dissimilar metals is the galling others have mentioned mentioned above...
    This discontinuity is really ****ing with my head.
    ETA: *^^* Not directed at anyone. I mean to say the forum's time traveling has been really confusing.

    Quote Originally Posted by bananaman View Post
    Thanks for the apparently time-traveling responses that actually appear to precede my first post (weird).
    Last edited by Eric D.; 08-07-11 at 12:40.
    B.A.S. Mechanical Engineering Technology

  7. #17
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    When tightening the barrel nut initially I do not torque it. I am simply tightening it and working the threads. I don't apply any anti-seize (http://www.midwayusa.com/viewproduct...tnumber=723099) until I get ready to do the final tightening of the barrel nut.



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  8. #18
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    Quote Originally Posted by Eric D. View Post
    I haven't seen it in other trades either. I thought it counter-intuitive as I have stripped many aluminum threads by repeated torquing. The goal is to align the holes/notches in the barrel nut for the gas tube while staying within 30-80 ft-lbs. Depending on how far the next notch is, you may approach the upper end of the limit. As I understand it, the 2-3 torque method helps you precisely get to the next notch while slowly working the threads without stripping them.



    Galvanic corrosion is a chemical damage and occurs between dissimilar metals because of their differences in electronegativity. It is usually only a major concern when the mating parts are in contact with an ionic solution (salt water)

    http://www.engineersedge.com/galvanic_capatability.htm

    Galling is a physical damage and is the bitch of aluminum. Its caused by two materials sliding against each other.

    http://en.wikipedia.org/wiki/Galling



    This discontinuity is really ****ing with my head.
    Sorry to be "****ing with your head."
    The read on wikipedia is interesting tho. It's ****ing with MY head now, because for 19 years of plumbing on M16's I've been calling it galling when a barrel nut siezes and apparently I've been incorrect. Damn those bastards that trained me!
    -Steve
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  9. #19
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    Copper anti-seize should not be used with aluminum as the copper content can cause dissimilar metal corrosion
    INSIDE PLAN OF BOX
    1. ROAD-RUNNER LIFTS GLASS OF WATER- PULLING UP MATCH
    2. MATCH SCRATCHES ON MATCH-BOX
    3. MATCH LIGHTS FUSE TO TNT
    4. BOOM!
    5. HA-HA!!

    -WILE E. COYOTE, AUTHOR OF "EVERYTHING I NEEDED TO KNOW IN LIFE, I LEARNED FROM GOLDBERG & MURPHY"

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  10. #20
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    I'm sure that sounds good in theory, but I have been using for close to 4 years and it has yet to cause an issue. I have used it on my personal weapons as well. YMMV

    Quote Originally Posted by MistWolf View Post
    Copper anti-seize should not be used with aluminum as the copper content can cause dissimilar metal corrosion



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